The present invention relates to threaded inserts, and more particularly to a structure of a threaded insert for use on drywalls or sheetrock.
Referring to FIG. 1, a first conventional threaded insert for use on drywalls comprises a cylindrical body 1, a flat drilling bit 2 formed on the front end of body 1 with three pointed spikes formed on the extreme end thereof, a flange 3 formed on the rear end of body 1, a thread 4 formed around the outer periphery of body 1, a bore 5 extending axially through body 1, and a roughly spoon shaped opening 6 formed on the base of drilling bit 2 and in communication with bore 5.
FIG. 2 shows the conventional threaded insert with a screw 7 inserted through bore 5 therein. The tip of screw 7 abuts spoon shaped opening 6 and causes drilling bit 2 to deflect laterally as the juncture of bit 2 with body 1 has been purposely weakened during manufacture.
This type of conventional threaded insert has several disadvantages which are enumerated hereunder.
1) As the drilling bit 2 has a comparable length with that of body 1, chips generated at the extreme end of the drilling bit 2 by the drilling procedure have a relatively long distance to travel before reaching bore 5, which often leads to clogging therein.
2) Also as a result of the length of drilling bit 2, the threaded insert may easily divert from the intended direction of travel during the drilling procedure.
3) As was mentioned above, the juncture of drilling bit 2 with body 1 has been purposely weakened during manufacture. However, this can often result in the premature breakage of drilling bit 2 during the drilling procedure, especially when drilling a wall material of relatively greater hardness.
4) If the threaded insert is used on a wall of a thickness greater than the length of the insert, the drilling bit 2 would remain embedded in the wall. A screw that is to be subsequently inserted into the insert would have difficulty in deflecting the drilling bit 2 and hence could not be fully inserted therein.
Referring to FIGS. 3 and 4, a second conventional threaded insert comprises an elongate, tapering body with a spiral threading formed thereon, a drilling tip 8 formed on the front end thereof, a flange formed on the rear end thereof, and a chip expelling hole 9 on the side thereof, adjacent to the drilling tip 8.
While this second type of conventional threaded insert has a more integral and sturdy structure than that of the first type described above, and lacks the extended drilling bit of the latter along with the disadvantages stemming from it, the position of the chip expelling hole 9 does not lead to efficient chip removal and is more prone to clogging than the first type of conventional threaded insert.
The threaded insert of the present invention, however, overcomes the deficiencies of the conventional threaded inserts described above with an improved structure as is fully described below.